The present inventive concept relates to nonvolatile memory devices and methods for fabricating the same, and more particularly, to three-dimensional nonvolatile memory devices capable of reducing the resistance of gate electrodes and preventing process defects, and methods for fabricating the same.
Nonvolatile memory devices can electrically erase and write (or program) data and can retain data even when the power supply is interrupted. Accordingly, the use of nonvolatile memory devices is increasing in various fields.
Nonvolatile memory devices include various types of memory cell transistors. Nonvolatile memory devices are classified into NAND-type nonvolatile memory devices and a NOR-type nonvolatile memory device, depending on the cell array structures. The NAND-type nonvolatile memory device and the NOR-type nonvolatile memory device have the advantages and disadvantages of high integration and high operation speed.
In particular, the NAND-type nonvolatile memory device is advantageous for high integration because it includes a cell string structure having a plurality of memory cell transistors connected in series. Also, the NAND-type nonvolatile memory device has a much higher data update speed than the NOR-type nonvolatile memory device because it uses an operation scheme of simultaneously changing data stored in a plurality of memory cell transistors. Due to such a high integration level and high update speed, the NAND-type nonvolatile memory device is widely used in portable electronic products requiring mass storage, such as digital cameras and MP3 players.
Research is being conducted to facilitate and promote the advantages of NAND-type nonvolatile memory devices. Accordingly, a three-dimensional nonvolatile memory device is being developed.